Long chain polyunsaturated fatty acids (LC-PUFAs) such as e.g. arachidonic acid (ARA), eicosapentaenoic (EPA) and docosahexaenoic (DHA) acids, dihomogammalinolenic (DHGLA) are of interest in general public health. For several years, these fatty acids have been investigated for their roles in metabolic pathways and regulation processes. LC-PUFAs are associated with numerous health benefits such as alleviated symptoms of arthritis and a reduced risk of cardiovascular and inflammatory diseases and growth development of infants.
A large number of food applications have been developed with marine oils, which are rich in LC-PUFA in the form of triacylglycerols.
LC-PUFAs in the form of triacylglycerols can be obtained by a process of mixing, milling and pressing the dried biomass with a vegetable oil as described for example in EP 1 239 022 and US 2006/0068076. Although this method is efficient in obtaining LC-PUFAs when present as triacylglycerol in the biomass, it leads to very poor results when the LC-PUFAs from the biomass are mainly in form of phospholipids.
Recently, there has been a growing interest in developing LC-PUFAs in the form of phospholipids to enhance their bioavailability, bioefficacy and oxidative stability. Indeed, some papers assume that the nature of the glyceride structures which act as dietary carrier (e.g. triacylglycerol, phospholipids, etc.) of DHA for instance could play an important role in the absorption rate of DHA at the enterocyte level and, therefore, in its accretion rate in the targeted organs such as brain or eyes.
Marine biomasses such as krill or crustaceans represent an interesting source of LC-PUFAs in the form of phospholipids. The lipid composition of krill may contain for example 40-60% phospholipids, 20-30% triacylglycerols, free fatty acids and sterols. The fatty acids EPA and DHA are esterified almost exclusively in the form of phospholipids, mainly in phosphatidylcholine.
Krill is commercially available as dried powder and krill oil is obtained by solvent extraction or supercritical carbon dioxide extraction. EP 1 417 211 describes a process by which extraction of phospholipids is carried out by treatment with organic solvents such as ethanol, acetone, hexane. This process however can lead to the degradation of the phospholipids and requires a number of purification steps in order to get rid of solvent traces. Furthermore, the oil obtained by such a process is not only expensive, but is also very bad in smell and taste.